A drug widely used to treat diabetes may also have the potential to help you stay slim according to the NHS.

It comes after a new study, conducted by researchers in Sweden and the US, which suggested that diabetes treatment Metformin had greater success in helping people keep the weight off compared to strict diet and exercise plans.

The research, which was funded by the US National Institutes of Health, involved over 1,066 people which were overweight or obese.

Scientists studied their weight loss progress very closely over a staggering 15 year period.

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The first year of the trial had shown most success for those on the diet and exercise plan, so during the second year everyone was offered this assignment - though participants on metformin were able to continue the treatment if they wished.

The recent observational follow-up then analysed the results of the 1,066 participants who lost 5% of their body weight in the first year.

This was conducted in order to see what factors from the beginning of the study predicted who was able to maintain at least 5% loss of weight after 15 years - including age and gender, treatment assigned in the first year and blood sugar levels.

What were the results?

Participants who developed diabetes during the trial were treated by their local healthcare provider (Image: Lynne Cameron/PA Wire)

Results for the first year of the trial showed that those on a strict diet and exercise plan had the most success in losing 5% of body weight.

Researchers found that 62.6% of these participants achieved the goal in 12 months, as compared to 28.5% of people taking metformin and 13.4% of participants in the placebo group.

And amongst participants who had lost this amount of body weight in the first year, the percentage who kept the weight off for the remaining 14 years was higher in the metformin group (56.5%).

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Participants who were assigned (or later chosen) the diet and exercise plan had a 48.9% success rate whilst 41.7% of the placebo group were successful in keeping the weight off.

The observational follow-up also discovered that the stronger predictors of maintaining weight loss over the 15 years were older age and weight loss in the first year of the study.

Researchers also revealed that, for those in the metformin group, a strong predictor of keeping the weight off was an active us of the treatment.

What has the NHS said?

The NHS said the study showed the 'potential' of the drug but asserted that more research is needed (Image: Dominic Lipinski/PA Wire)

The NHS noted that the study was a post-hoc analysis - meaning observation was conducted after the initial results were recorded.

This secondary analysis "makes the results more prone to bias" as researchers may have been primed to spot certain results that agreed with their intentions.

It's also important to note that the follow-up (and original trial) focus on a "small section" of participants who had lost 5% of body weight in the first 12 months - so 70% of those who started the trial were not included.

The original study has other limitations though, said the NHS, such as the potential for people to have switched to other treatments (than originally assigned) or participants having stopped treatments altogether during the 15 years.

The NHS reminded that whilst metformin is widely used as diabetes treatment, "it is not licensed as a weight loss medicine" - and such a change would require the manufacturers to conduct additional research.

It however acknowledged that the drug "may have potential as an aid for people needing to maintain weight loss in future."

The health service concluded though that the most successful weight-loss treatment is diet and exercise, as illustrated in the initial 12 months' results.